Semiconductor device and metering apparatus

ABSTRACT

A semiconductor device includes: an oscillator; a semiconductor chip that includes an oscillation circuit connected to the oscillator, a timer circuit that generates a timing signal of a frequency according to a oscillation frequency of the oscillation circuit, and a frequency correction section that corrects a frequency of the timing signal based on temperature data; and a discrete device that includes at least one of a temperature sensing device that detects a peripheral temperature, that supplies the detected temperature as temperature data to the frequency correction section, and that is provided as a separate body to the semiconductor chip, or a capacitor that is electrically connected to both the oscillator and the oscillation circuit and that is provided as a separate body to the semiconductor chip, wherein the oscillator, the semiconductor chip and the discrete device are contained within a single package.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 14/025,721, filed onSep. 12, 2013, and allowed on Jul. 23, 2015, which claimed priorityunder 35 USC 119 from Japanese Patent Application No. 2012-203060, filedon Sep. 14, 2012. The disclosures of these applications are incorporatedby reference herein.

BACKGROUND

1. Technical Field

The present invention relates to a semiconductor device and to ametering apparatus, and in particular relates to a semiconductor deviceincluding an oscillation circuit containing an oscillator, and to ametering apparatus containing such a semiconductor device.

2. Description of the Related Art

There has been growing interest recently into “smart meters” that areimplement by adding a high performance communication function to ameter, such as electricity, gas or water meter, so as to performautomatic reading and various types of service. With smart meters,various management and control functions are performed whilstascertaining consumer usage history of electricity, gas or water in realtime. Development is accordingly proceeding into meters that have anin-built semiconductor device with a time measurement function thataccurately logs times irrespective of the environment in which the meteris installed. Semiconductor devices that have a time measurementfunction are generally configured to include an oscillator, anoscillation circuit that is connected to the oscillator, and a timercircuit that generates a timing signal of a specific frequency from anoutput signal of the oscillator. The oscillation circuit and the timercircuit are formed in the semiconductor integrated circuit.

As a semiconductor device with an oscillator and a semiconductor chipwith an oscillation circuit connected to the oscillator in-built in thesame package, Japanese Patent Application Laid-Open (JP-A) No.2009-213061 describes using external terminals provided on an outer faceof a vibrator and disposing the vibrator on one face of a wiring board,and disposing a semiconductor chip that is connected to the vibrator tocause it to oscillate disposed on the one face of the wiring board,alongside the vibrator. A resin molding member is then provided on theone face of the wiring board so as to cover the semiconductor chip.

There is also a circuit device described in JP-A No. 2010-34094 that isequipped with an IC chip that includes an oscillator, and a circuitsection that configures an oscillation circuit for electrical connectionto the oscillator. In this circuit device, the oscillator has pluralelectrodes, and there are plural oscillator pads corresponding to theplural electrodes of the IC chip, and the oscillator is electricallyconnected to the plural oscillator pads on the IC chip by its pluralelectrodes facing towards the plural oscillator pads on the IC chipthrough an Anisotropic Conductive Film (ACF).

SUMMARY OF THE INVENTION

An exemplary aspect of the present disclosure is a semiconductor devicethat includes: an oscillator; a semiconductor chip that includes anoscillation circuit connected to the oscillator, a timer circuit thatgenerates a timing signal of a frequency according to a oscillationfrequency of the oscillation circuit, and a frequency correction sectionthat corrects a frequency of the timing signal based on temperaturedata; and a discrete device that includes at least one of a temperaturesensing device that detects a peripheral temperature, that supplies thedetected temperature as temperature data to the frequency correctionsection, and that is provided as a separate body to the semiconductorchip, or a capacitor that is electrically connected to both theoscillator and the oscillation circuit and that is provided as aseparate body to the semiconductor chip, wherein the oscillator, thesemiconductor chip and the discrete device are contained within a singlepackage.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments of the present invention will be described indetail based on the following figures, wherein:

FIG. 1 is a perspective view of a configuration of an integratingelectricity meter according to a first exemplary embodiment;

FIG. 2 is plan view illustrating a configuration of a semiconductordevice according to the first exemplary embodiment of the presentinvention;

FIG. 3 is a cross-section taken along line 3-3 of FIG. 2;

FIG. 4 is perspective view illustrating a configuration of an oscillatoraccording to the first exemplary embodiment of the present invention;

FIG. 5 is a perspective view illustrating a configuration of atemperature sensing device according to the first exemplary embodimentof the present invention;

FIG. 6 is a functional block diagram of a semiconductor device accordingto the first exemplary embodiment of the present invention;

FIG. 7 is a flow chart illustrating a flow of data storage processing inthe first exemplary embodiment of the present invention;

FIG. 8 is a flow chart illustrating a flow of frequency error derivationprocessing according to the first exemplary embodiment of the presentinvention;

FIG. 9A is a timing chart illustrating operation of a measurementcounter and a reference counter in frequency error derivation processingaccording to an exemplary embodiment of the present invention;

FIG. 9B is a timing chart illustrating operation of a measurementcounter and a reference counter in frequency error derivation processingaccording to an exemplary embodiment of the present invention;

FIG. 10 is a flow chart illustrating a flow of frequency correctionprocessing according to the first exemplary embodiment of the presentinvention;

FIG. 11 illustrates a relationship between temperature and frequencydeviation in an oscillation circuit;

FIG. 12A is a plan view illustrating a configuration of a semiconductordevice according to a second exemplary embodiment of the presentinvention;

FIG. 12B is cross-section taken on 12 b-12 b of FIG. 12A;

FIG. 13 is a functional block diagram of a semiconductor deviceaccording to a second exemplary embodiment of the present invention;

FIG. 14 is a perspective view illustrating a configuration of acapacitor according to the second exemplary embodiment of the presentinvention;

FIG. 15 is a graph illustrating temperature characteristics of acapacitor according to a second exemplary embodiment of the presentinvention;

FIG. 16 is a perspective view illustrating a partial configuration of asemiconductor device according to a second exemplary embodiment of thepresent invention;

FIG. 17A is a plan view illustrating a configuration of a semiconductordevice according to a third exemplary embodiment of the presentinvention;

FIG. 17B is a cross-section taken on line 17 b-17 b in FIG. 17A;

FIG. 18 is a functional block diagram illustrating a semiconductordevice according to the third exemplary embodiment of the presentinvention;

FIG. 19 is a functional block diagram illustrating a semiconductordevice according to a fourth exemplary embodiment of the presentinvention;

FIG. 20 is a flow chart illustrating a flow of frequency correctionprocessing according to the fourth exemplary embodiment of the presentinvention;

FIG. 21 is a functional block diagram of a semiconductor deviceaccording to a fifth exemplary embodiment of the present invention;

FIG. 22 is a flow chart illustrating a flow of frequency correctionprocessing according to the fifth exemplary embodiment of the presentinvention;

FIG. 23 is a flow chart illustrating another flow of frequencycorrection processing according to the fifth exemplary embodiment of thepresent invention;

FIG. 24 is a functional block diagram of a semiconductor deviceaccording to a sixth exemplary embodiment of the present invention; and

FIG. 25 is a perspective view illustrating a configuration of asemiconductor module according to an exemplary embodiment of the presentinvention.

DETAILED DESCRIPTION

Explanation follows regarding exemplary embodiments of the presentinvention, with reference to the drawings. Note that the same orequivalent configuration elements and portions are allocated with thesame reference numerals in each of the drawings.

First Exemplary Embodiment Configuration of Integrating ElectricityMeter

FIG. 1 is a perspective view of an integrating electricity meter 10equipped with a semiconductor device 1 (FIG. 2) according to a firstexemplary embodiment. The integrating electricity meter 10 is attachedto a fixing plate 102 that is fixed to an external wall 100 of forexample a house. The integrating electricity meter 10 principallyincludes: a main body 12; a transparent cover 14 that covers the mainbody 12; and a connection section 16 provided at a lower portion of themain body 12.

A power supply-side cable 18 and a load-side cable 20 are connected frombelow the connection section 16 and supply current to the integratingelectricity meter 10. The main body 12 is a box body of rectangularshape when viewed face on (referred to below as plan view). Thesemiconductor device 1 and a power consumption metering circuit 22 aremounted on a base plate inside the main body 12. The power consumptionmetering circuit 22 serves as a metering section that generates timingdata based on a measuring signal output from the semiconductor device 1and measures integral power consumption associated with the timing data.Namely, the power consumption metering circuit 22 meters powerconsumption per unit time and integral power consumption for eachseparated time band. A liquid crystal display 15 is provided with itslength aligned in a transverse direction on the front face of the mainbody 12. The liquid crystal display 15 displays such information as thepower consumption per unit time as measured by the power consumptionmetering circuit 22 and the integral power consumption used in each timeband. Note that although the integrating electricity meter 10 accordingto the present exemplary embodiment is an electronic electricity meterin which the power consumption metering circuit 22 is employed as themetering section, there is no limitation thereto. A rotating diskinduction type electricity meter may for example be employed formeasuring the power consumption. Moreover, although an explanation isgiven in the present exemplary embodiment of an example of theintegrating electricity meter 10 that performs metering of powerconsumption as a metering device, a device may be employed that metersanother metering commodity associated against time data other thanelectricity, such as for example water or gas.

Semiconductor Device Structure

FIG. 2 is a plan view illustrating a configuration of the semiconductordevice 1 according to a first exemplary embodiment of the presentinvention, FIG. 3 is a cross-section taken on line 3-3 of FIG. 2. Notethat in the FIG. 2 the left-right direction is the arrow X direction,and the up-down direction is the arrow Y direction, and the Z directionis a direction orthogonal to the X-Y plane. The external shape of thesemiconductor device 1 is a rectangular shape in plan view, and thesemiconductor device 1 includes a lead frame 26 that acts as aframework, a temperature sensing device (temperature sensor) 27 and anoscillator 28 mounted to a first main face 25A of a die pad 26Aconfiguring the lead frame 26, a semiconductor chip 30 that is mountedto a second main face 25B of the lead frame 26 on the opposite side tothe first main face 25A of the die pad 26A, and molding resin 32 thatserves as a sealing member for these members mounted on the die pad 26A.

The lead frame 26 is a plate member formed from a flat sheet of a metalsuch as copper (Cu) or an iron (Fe) and nickel (Ni) alloy, by pressingout with a press. The lead frame 26 includes: a die pad 26A provided ata central portion; hanging leads 26B that extend outwards from the diepad 26A along diagonal lines; and plural leads (terminals) 38 providedbetween adjacent of the hanging leads 26B.

The leads 38 are long thin members extending towards a central portionof the die pad 26A, with plural of the leads 38 formed at a specificseparation around the periphery of the die pad 26A. In the presentexemplary embodiment there are 16 lines of the leads 38 formed betweeneach adjacent pair of the hanging leads 26B. The leads 38 are configuredfrom inner leads 38A that are positioned on the die pad 26A side and areburied in within molding resin 32, and outer leads 38B that arepositioned at the outer peripheral end side of the semiconductor device1 and exposed from the molding resin 32. The inner leads 38A are presseddown by a press so as to be lower than the die pad 26A and extendparallel to the die pad 26A (see FIG. 3). The leading end portions ofthe inner leads 38A nearest to the die pad 26A are covered with anelectroplated film 40. In the present exemplary embodiment, as anexample, the electroplated film 40 is formed from silver (Ag), howeverthere is no limitation thereto, and for example an electroplated filmformed from gold (Au) may be employed.

The outer leads 38B are exposed from the molding resin 32, and are bentdownwards with their leading end portions parallel to the inner leads38A. Namely the outer leads 38B are configured as gull-wing leads. Theouter leads 38B are covered by an electroplated solder film. Substanceswhich may be employed as an electroplated solder film include forexample tin (Sn), a tin (Sn) and lead (Pb) alloy, and a tin (Sn) andcopper (Cu) alloy.

The die pad 26A is a flat plate shaped formed with a rectangular shapein plan view. In the die pad 26A, through holes 26C, 26D, 26E, 26F areformed piercing from the first main face 25A to the second main face 25Bof the die pad 26A. The through holes 26C to 26F are each respectivelyformed in a rectangular shape. In the present exemplary embodiment anexample is given in which each of the through holes 26C to 26F is in astate surrounded on four sides by the lead frame 26, however the throughholes 26C to 26F may be provided as C-shaped cutouts open on one side.

The through holes 26C and 26D are placed alongside each other in the Ydirection, and a region between the through holes 26C and 26D configuresa temperature sensing mounting beam 41 serving as a temperature sensingdevice mounting region for mounting the temperature sensing device 27.Similarly, the through holes 26E and 26F are placed alongside each otherin the Y direction, and a region between the through holes 26E and 26Fconfigures an oscillator mounting beam 42 serving as an oscillatormounting region for mounting the oscillator 28.

The oscillator 28 is joined to the oscillator mounting beam 42 on thefirst main face 25A side of the die pad 26A. In the present exemplaryembodiment the oscillator 28 employed is a surface mounted type ofoscillator with an oscillation frequency of 32.768 kHz for mounting togeneral electronic devices.

FIG. 4 is a perspective view illustrating a configuration of theoscillator 28. Note that in FIG. 4 the through holes 26E and 26F formedin the die pad 26A and the oscillator mounting beam 42 are illustratedtogether with the oscillator 28. The oscillator 28 is configuredincluding a vibrating reed 281, a rectangular box shaped package body282 that houses the vibrating reed 281 and a lid 283. The vibrating reed281 is a quartz oscillator crystal, with excitation electrodes 281Aformed as a film on the surface of a tuning fork shaped quartz crystalformed from an artificial quartz crystal. The vibrating reed 281vibrates due to a piezoelectric effect when current flows in theexcitation electrodes 281A. The vibrating reed 281 is not limited to atuning fork shape and an AT cut quartz crystal may be employed. Otherthan quartz, vibrating reeds formed from lithium tantalate (LiTaO3) orlithium niobate (LiNbO3) may also be employed. A MEMS vibrating reedformed from silicon may also be employed.

The package body 282 is a box body with an open upper portion. A seat284 affixed with the vibrating reed 281 is formed at one lengthdirection end side of a bottom portion of the package body 282. A baseportion of the vibrating reed 281 is fixed to the seat 284, with thevibrating reed 281 hermetically sealed by the package body 282 and thelid being 283 joined together in a vacuum state so as to enablevibration. The two ends on the lower face of the package body 282 areformed with the external electrodes 285 as terminals that areelectrically connected to the excitation electrodes 281A of thevibrating reed 281. The external electrodes 285 are formed separatedfrom each other at a specific distance L1. The specific distance L1between the external electrodes 285A is formed so as to be narrower thanthe width L2 of the oscillator mounting beam 42.

The external electrodes 285 are formed with widths (longer sides) thesame as the width (the shorter side) of the package body 282. Asillustrated in FIG. 2, the size of the external electrodes 285 is largerthan the size of electrode pads 50 formed to the semiconductor chip 30and oscillator electrode pads 51 a, both described later. The externalelectrodes 285 are also formed smaller than the through holes 26E and26F of the die pad 26A. The oscillator 28 is joined to the first mainface 25A of the die pad 26A so as to straddle the oscillator mountingbeam 42. The two external electrodes 285 formed at the two ends of theoscillator 28 are accordingly exposed to the second main face 25B sideof the die pad 26A through the respective through holes 26E and 26F.

The temperature sensing device 27 is joined to the temperature sensingdevice mounting beam 41 formed between the through holes 26C and 26D onthe first main face 25A side of the die pad 26A. In the presentexemplary embodiment, the temperature sensing device 27 is a surfacemounted type of thermistor whose resistance changes according to changesin temperature. The temperature sensing device 27 is for exampleconfigured by a ceramic semiconductor with principle materials oftransition metal oxides of principally Mn, Co, Ni. Note that thetemperature sensing device 27 may be configured from a conductive bariumtitanate based oxide semiconductor doped with minute quantities of rareearth elements. In such cases the resistance increases as thetemperature rises.

FIG. 5 is a perspective view of a configuration of the temperaturesensing device 27. Note that in FIG. 5, the through holes 26C and 26Dformed in the die pad 26A and the temperature sensing device mountingbeam 41 are illustrated together with the temperature sensing device 27.The temperature sensing device 27 is configured including a resistor 271configured from a ceramic semiconductor or a barium titanate based oxidesemiconductor, and external electrodes 272 provided at both ends of theresistor 271. A distance L3 between the external electrodes 272 is setlarger than a width fold line L4 of the temperature sensing devicemounting beam 41. As illustrated in FIG. 2, the size of the externalelectrodes 272 is larger than that of the electrode pads 50 andtemperature sensing device electrode pads 51 b formed to thesemiconductor chip 30. The through holes 26C and 26D of the die pad 26Aare formed larger than the external electrodes 272. The temperaturesensing device 27 is joined to the first main face 25A of the die pad26A so as to straddle the temperature sensing device mounting beam 41.The two external electrodes 272 at the two ends of the temperaturesensing device 27 are accordingly exposed to the second main face 25B ofthe die pad 26A through the through holes 26C and 26D.

As illustrated in FIG. 2 and FIG. 3, the semiconductor chip 30 ismounted to the second main face 25B of the die pad 26A at a centralportion of the die pad 26A. The semiconductor chip 30 is disposed so asto partially close off the through holes 26C to 26F formed in the diepad 26A, with the temperature sensing device 27 and the oscillator 28partially overlapping with each other in a direction parallel to thefirst and second main faces 25A, 25B (the X-Y plane direction). At theportions of the through holes 26C to 26F not closed off by thesemiconductor chip 30, the external electrodes 272 of the temperaturesensing device 27 and the external electrodes 285 of the oscillator 28are exposed to the second main face 25B side mounted with thesemiconductor chip 30. Namely, as illustrated in FIG. 2, the externalelectrodes 272 of the temperature sensing device 27 are exposed to thesecond main face 25B side through the through holes 26C and 26Dextending at the outside on the left hand side edge of the semiconductorchip 30, and the external electrodes 285 of the oscillator 28 areexposed to the second main face 25B side through the through holes 26Eand 26F extending at the outside on the right hand side edge of thesemiconductor chip 30.

The plural electrode pads 50 are provided at an outer peripheral portionof each of the sides of the semiconductor chip 30 so as to form arectangular shape. The electrode pads 50 are respectively electricallyconnected to the inner leads 38A through bonding wires 52. Note that inthe present exemplary embodiment, the number of the electrode pads 50matches the number of the leads 38, and there are 16 individualelectrode pads 50 provided at each edge of the semiconductor chip 30.However there is no limitation thereto, and more of the electrode pads50 for other purposes may be provided than the number of leads 38.

The oscillator electrode pads 51 a connected to the oscillator 28 areprovided separately to the electrode pads 50 on the oscillator 28 sideedge of the semiconductor chip 30. Two of the oscillator electrode pads51 a are provided above the oscillator mounting beam 42 that is at a Ydirection central portion of the semiconductor chip 30. The oscillatorelectrode pads 51 a are respectively electrically connected by bondingwires 53 a to the external electrodes 285 of the oscillator 28 that areexposed to the second main face 25B side of the die pad 26A through thethrough holes 26E and 26F. Note that the bonding wires 52 and thebonding wires 53 a are wire shaped conductive members formed from ametal such as gold (Au), aluminum (Al) or copper (Cu). The oscillatorelectrode pads 51 a connected to oscillator 28 are provided separatedfrom the electrode pads 50 provided on the same side of thesemiconductor chip 30. In other words, the separation distance betweenthe oscillator electrode pads 51 a and the electrode pads 50 is longerthan the separation distances between the inter-electrode pad 50distance.

The bonding wires 53 a that connect together the oscillator electrodepads 51 a and the external electrodes 285 of the oscillator 28, and thebonding wires 52 that connect together the electrode pads 50 and theinner leads 38A, are formed with a 3-D intersection. Namely, asillustrated in FIG. 3, the bonding wires 52 are formed so as to straddlethe bonding wires 53 a. In order to prevent shorting from occurringbetween the bonding wires 52 and 53 a, the apex of the bonding wires 53a is formed in a loop so as to be lower (less far away from the leadframe 26) than the apex of the bonding wires 52. Note that the height ofthe apex of the all the bonding wires 52 may be made higher than theheight of the apex of the bonding wires 53 a, or configuration may bemade such that the height of the apex of at least each of the bondingwires 52 that form the 3-D intersection with the bonding wires 53 a aremade higher than the height of the apex of the bonding wires 53 a.

Moreover, the center of the semiconductor chip 30 and the center CP ofthe rectangular shaped oscillator 28 are disposed so as be alignedsubstantially parallel to the X-axis direction. Namely, the width of anydisplacement of the center CP of the oscillator 28 from the X-axis inthe Y-axis direction is narrower than the Y-axis direction width of thecentral portion. In this layout state, the oscillator electrode pads 51a provided in the vicinity of the center of a given side of thesemiconductor chip 30 and the external electrodes 285 disposed at adistance from the two length direction ends of the oscillator 28 areconnected together by the bonding wires 53 a. Moreover, the electrodepads 50 are disposed in a row so as to be disposed on each side of theoscillator electrode pads 51 a, and the inner leads 38A are disposed ina row along the Y-axis direction that is parallel to the electrode pads50, are also connected together by the bonding wires 52.

Moreover, due to providing the oscillator electrode pads 51 a separatedfrom the electrode pads 50, the bonding wires 52 pass through portionswhere the bonding wires 53 a are lower than the semiconductor chip 30.Namely, the bonding wires 52 can achieve a 3-D intersection thatefficiently avoids crossing by passing in the vicinity of the apex ofthe bonding wires 53 a. Moreover, being able to suppress the height ofthe apex of the bonding wires 52 enables the height of the package toalso be made low.

Moreover, the connection positions of the bonding wires 53 a to theexternal electrodes 285 of the oscillator 28 are shifted in the X-axisdirection further to the inner leads 38A side than the central positionof the oscillator 28. Adopting such connections enables contact of thebonding wires 53 a with the edge of the semiconductor chip 30 to bereduced. Moreover, the connection positions are also shifted in theY-axis direction more towards the direction of the oscillator 28 centerthan the center of the external electrodes 285 of the oscillator 28.Adopting such connections enables the number of times of cross-over withthe bonding wires 52 to be reduced.

The temperature sensing device electrode pads 51 b that are connected tothe temperature sensing device 27 are provided separately to theelectrode pads 50 on the edge of the semiconductor chip 30 on thetemperature sensing device 27 side. Two of the temperature sensingdevice electrode pads 51 b are provided above the temperature sensingdevice mounting beam 41 at a Y direction central portion of thesemiconductor chip 30. The temperature sensing device electrode pads 51b are respectively electrically connected by bonding wires 53 b to theexternal electrodes 272 of the temperature sensing device 27 exposed tothe second main face 25B side of the die pad 26A through the throughholes 26C and 26D.

The positional relationship of the electrode pads 50 to the temperaturesensing device electrode pads 51 b is similar to the positionalrelationship of the electrode pads 50 to the oscillator electrode pads51 a described above. Hence the positional relationship between thebonding wires 53 b and the bonding wires 52 is also similar to thepositional relationship between the bonding wires 53 a and the bondingwires 52 on the oscillator 28 side. Namely, the temperature sensingdevice electrode pads 51 b connected to the temperature sensing device27 are provided separated from the electrode pads 50 that are providedon the same side of the semiconductor chip 30. In other words, theseparation distance between the temperature sensing device electrodepads 51 b and the electrode pads 50 is longer than the inter-electrodepad 50 distance.

The bonding wires 53 b that connect together the temperature sensingdevice electrode pads 51 b and the external electrodes 272 of thetemperature sensing device 27, and the bonding wires 52 that connecttogether the electrode pads 50 and the inner leads 38A, are formed witha 3-D intersection. Namely, as illustrated in FIG. 3, the bonding wires52 are formed so as to straddle the bonding wires 53 b. In order toprevent shorting from occurring between the bonding wires 52 and 53 b,the apex of the bonding wires 53 b is formed as a loop so as to be lower(less far away from the lead frame 26) than the apex of the bondingwires 52.

Moreover, the center of the semiconductor chip 30 and the center of thetemperature sensing device 27 are disposed so as be alignedsubstantially parallel to the X-axis direction. Namely, the width of anydisplacement of the center of the temperature sensing device 27 from theX-axis in the Y-axis direction is narrower than the Y-axis directionwidth of the central portion. In this layout state, the temperaturesensing device electrode pads 51 b and the external electrodes 272disposed at a distance from the two length direction ends of thetemperature sensing device 27 are connected together by the bondingwires 53 b. Moreover, the electrode pads 50 disposed in a row so as tobe disposed on each side of the temperature sensing device electrodepads 51 b, and the inner leads 38A disposed in a row along the Y-axisdirection that is parallel to the electrode pads 50, are also connectedtogether by the bonding wires 52.

Moreover, due to providing the temperature sensing device electrode pads51 b separated from the electrode pads 50, the bonding wires 52 passthrough at a portion where the bonding wires 53 b are lower than thesemiconductor chip 30. Namely, the bonding wires 52 can achieve a 3-Dintersection that efficiently avoids crossing by passing in the vicinityof the apex of the bonding wires 53 b. Moreover, being able to suppressthe height of the apex of the bonding wires 52 enables the height of thepackage to also be made low.

Moreover, the connection positions of the bonding wires 53 b to theexternal electrodes 272 of the temperature sensing device 27 are shiftedin the X-axis direction further to the inner leads 38A side than thecentral position of the temperature sensing device 27. Adopting suchconnections enables contact of the bonding wires 53 b with the edge ofthe semiconductor chip 30 to be reduced. Moreover, the connectionpositions are also shifted in the Y-axis direction more towards thedirection of the temperature sensing device 27 center than the center ofthe external electrodes 272 of the temperature sensing device 27.Adopting such connections enables the number of times of cross-over withthe bonding wires 52 to be reduced.

The temperature sensing device 27, the oscillator 28, the semiconductorchip 30 and the lead frame 26 are sealed with the molding resin 32. Themolding resin 32 is poured such that internal voids do not form. Adistance H1 from the surface of the molding resin 32 on the temperaturesensing device 27 and the oscillator 28 mounting side to the center ofthe inner leads 38A, is longer than a distance H2 from the surface ofthe molding resin 32 on the semiconductor chip 30 mounting side to thecenter of the inner leads 38A. In the present exemplary embodiment, thedistance H1 is twice the distance H2 or greater. A distance H3 from thesurface of the molding resin 32 on the semiconductor chip 30 mountingside to the center of the die pad 26A is also longer than the distanceH2 from the surface of the molding resin 32 on the semiconductor chip 30mounting side to the center of the inner leads 38A. Note that in thepresent exemplary embodiment a thermoset epoxy resin containing silicabased filler is employed as the molding resin 32, however there is nolimitation thereto, and a thermoplastic resin may for example beemployed therefor.

Explanation next follows regarding a functional configuration of thesemiconductor device 1 according to the present exemplary embodiment.FIG. 6 is a functional block diagram of the semiconductor device 1according to a first exemplary embodiment of the present invention. Asillustrated in FIG. 6, the semiconductor chip 30 is in-built with anoscillation circuit 61, a frequency divider circuit 62, a timer circuit63, a control circuit 60, a registry section 70, a measurement counter81 and a reference counter 82.

The oscillation circuit 61 is electrically connected to the oscillator28 by the bonding wires 53 a, and includes a capacitor and an amplifier(not illustrated in the drawings), for prolonging oscillation, thattogether with the oscillator 28 configure the oscillating circuit. Theoscillation circuit 61 generates an output signal at a frequency of32.768 kHz. The frequency divider circuit 62 generates an output signalof for example 1 Hz by outputting at every 15th cycle of the signaloutput from the oscillation circuit 61. Based on a frequency correctionamount supplied from the control circuit 60, the timer circuit 63corrects frequency fluctuations in the output signal of the frequencydivider circuit 62 accompanying changes in temperature, and outputs thisas a timer signal. Namely, the timer signal is a 1 Hz signal withimproved higher precision.

The temperature sensing device 27 is a thermistor whose resistancechanges according to the peripheral temperature, as described above. Thecontrol circuit 60 is connected to the temperature sensing device 27 bythe bonding wires 53 b, and detects the peripheral temperature bymeasuring the resistance of the temperature sensing device 27. Thetemperature sensing device 27 is mounted on the first main face 25A ofthe die pad 26A so as to be alongside the oscillator 28, and so isdisposed in substantially the same temperature environment as that ofthe oscillator 28. The temperature detected by the temperature sensingdevice 27 accordingly substantially matches the temperature of theoscillator 28.

The registry section 70 is configured to include plural registers 71 to75 for storing various data for correcting frequency fluctuations of theoutput signals of the oscillation circuit 61 and the frequency dividercircuit 62 accompanying temperature changes. Namely, the registrysection 70 is configured by a temperature measurement value register 71,a low temperature register 72, a room temperature register 73, a hightemperature register 74 and a frequency correction register 75. Thetemperature measurement value register 71 is a register that stores dataindicating the temperature measured by the temperature sensing device27. The low temperature register 72 is a register that stores dataindicating, in a low temperature environment, the temperature measuredby the temperature sensing device 27 and a frequency error of the outputsignal of the oscillation circuit 61 derived by the control circuit 60therein. The room temperature register 73 is a register that stores dataindicating, in a room temperature environment, the temperature measuredby the temperature sensing device 27 and a frequency error of the outputsignal of the oscillation circuit 61 derived by the control circuit 60.The high temperature register 74 is a register that stores dataindicating, in a high temperature environment, the temperature measuredby the temperature sensing device 27 and a frequency error of the outputsignal of the oscillation circuit 61 derived by the control circuit 60.The frequency correction register 75 is a register that stores afrequency correction amount derived by the control circuit 60. Theseregisters 71 to 75 are connected to the control circuit 60 through adata bus 76. The control circuit 60 writes data to and reads data fromeach of the registers 71 to 75 through the data bus 76.

The measurement counter 81 is a counter that counts the number of pulsesof the output signal (32.768 kHz) of the oscillation circuit 61 undercontrol from the control circuit 60. The reference counter 82 is acounter that counts the number of pulses of an externally suppliedreference clock signal under control from the control circuit 60. Thereference clock signal is supplied from outside through the leads 38,and is a pulse signal with high frequency precision, for example of 10MHz. Note that although the frequency of the reference clock signal isarbitrary, it is preferably higher than the oscillation frequency(32.768 kHz) of the oscillation circuit 61. The count values of themeasurement counter 81 and the reference counter 82 are supplied to thecontrol circuit 60. The control circuit 60 derives frequency errors inthe output signal of the oscillation circuit 61 based on the countvalues supplied from the measurement counter 81 and the referencecounter 82.

The control circuit 60 is configured by a computer equipped to include aROM stored with a data storage processing program (see FIG. 7), afrequency error derivation program (see FIG. 8) and a frequencycorrection processing program (see FIG. 10), as described later, a CPUfor executing these programs, and RAM for temporarily storing processingcontent of the CPU. When executing the various programs, the controlcircuit 60 performs processing to write and read the derived frequencyerrors to and from the registry section 70, processing such as tocontrol operation of the measurement counter 81 and the referencecounter 82, and derives frequency errors based on the data stored in theregistry section 70, and supplies these frequency errors to the timercircuit 63.

Data Storage Processing

Explanation follows regarding data storage processing in which thecontrol circuit 60 of the semiconductor device 1 stores various data inthe registry section 70 for deriving a frequency correction amount. Thedata storage processing is performed for example during shippinginspection executed prior to shipping the semiconductor device 1.

During shipping inspection, the semiconductor device 1 is first placedinside a constant temperature chamber in which the temperature set at aspecific temperature. The control circuit 60 executes the data storageprocessing when a control signal to execute the data storage processingis externally input through the leads 38. Note that the control signalcontains data indicating which temperature is set in the constanttemperature chamber out of the room temperature, the high temperatureand the low temperature. FIG. 7 is a flow chart illustrating a flow ofprocessing of a data storage processing program executed by the controlcircuit 60. The program is pre-stored on a recording medium (ROM) of thecontrol circuit 60.

At step S101, the control circuit 60 determines whether or not aspecific period of time (for example several hours) has elapsed fromwhen the control signal to execute the data storage processing wasinput. Note that the specific period of time is preferably at least aperiod of time required for the internal temperature of thesemiconductor device 1 to reach a steady state.

If determined at step S101 that the specific period of time has elapsed,then the control circuit 60 acquires at step S103 a temperaturemeasurement value using the temperature sensing device 27, and storesthe acquired measurement value in the temperature measurement valueregister 71. The temperature sensing device 27 is mounted on the firstmain face 25A of the die pad 26A so as to be alongside the oscillator 28and so the temperature environment is substantially the same as that ofthe oscillator 28. Consequently, the temperature detected by thetemperature sensing device 27 is substantially the same as thetemperature of the oscillator 28.

At step S105, the control circuit 60 performs frequency error derivationprocessing to derive the frequency error in the output signal of theoscillation circuit 61. The frequency error in the output signal of theoscillation circuit 61 is the amount displaced from the targetfrequency, that is 32.768 kHz. FIG. 8 is flow chart illustrating a flowof frequency error derivation processing according to the presentexemplary embodiment and corresponding to step S105. FIG. 9A and FIG. 9Bare timing charts illustrating operation of the measurement counter 81and the reference counter 82 in the frequency error derivationprocessing. FIG. 9A illustrates a count start time, and FIG. 9Billustrates a count stop time.

At step S201, the control circuit 60 supplies the measurement counter 81with a control signal to start count operation. On receipt of therelevant control signal, the measurement counter 81 starts counting thenumber of pulses of the oscillation circuit 61 output signal, and alsosupplies a measurement count operation signal indicating that countoperation has started to the reference counter 82. On receipt of thismeasurement count operation signal the reference counter 82 startscounting the number of pulses of the reference clock signal externallysupplied through the leads 38. Namely, count operation is started atsubstantially the same time in the measurement counter 81 and thereference counter 82. In the present exemplary embodiment, the referenceclock signal is a high frequency precision 10 MHz signal generated by asignal generating device, not illustrated in the drawings, and suppliedto the semiconductor device 1. The count values of the measurementcounter 81 and the reference counter 82 are supplied to the controlcircuit 60.

At step S203, the control circuit 60 determines whether or not the countvalue of the measurement counter 81 has reached a predetermined specificvalue (corresponding to 32768 counts per second in the present exemplaryembodiment). The control circuit 60 continues the count operation of themeasurement counter 81 and the reference counter 82 when the count valueof the measurement counter 81 is determined not yet to have reached thespecific value. However, when determined that the count value of themeasurement counter 81 has reached the specific value, at step S205, thecontrol circuit 60 supplies a control signal to stop the count operationto the measurement counter 81. On receipt of the relevant control signalthe measurement counter 81 stops counting the number of pulses in theoscillation circuit 61 output signal and supplies a measurement countoperation signal indicating that the count operation has stopped to thereference counter 82. On receipt of this measurement count operationsignal, the reference counter 82 stops counting the number of pulses inthe reference clock signal. Namely, the count operation is stopped atsubstantially the same time in the measurement counter 81 and thereference counter 82. The count values of the measurement counter 81 andthe reference counter 82 are supplied to the control circuit 60.

At step S207, the control circuit 60 derives the frequency error in theoutput signal of the oscillation circuit 61 based on the count values ofthe measurement counter 81 and the reference counter 82. Namely, thecontrol circuit 60 compares the count value of the number of pulses inthe output signal of the oscillation circuit 61 (namely 32768) againstthe count value of the reference clock signal obtained during the sameperiod of time, and thereby derives the frequency error of the outputsignal of the oscillation circuit 61. In the present exemplaryembodiment, the frequency of the reference clock signal is 10 MHz and soif the count value of the reference counter 82 is 10000000 (in decimalnumbering) then 1 second can be accurately timed by the output signal ofthe oscillation circuit 61. Consequently, in this case, the frequencyerror of the oscillation circuit 61 would be 0, and there would be afrequency correction amount of 0. However, for example, if for examplethe count value of the reference counter 82 is 10000002 (in decimalnumbering) then it can be estimated that the frequency of the outputsignal of the oscillation circuit 61 is slow by 0.2 ppm (parts permillion). Thus in such a case the frequency of the output signal of theoscillation circuit 61 needs to be corrected by this error amount,namely sped up by 0.2 ppm. Namely the frequency correction amount is+0.2 ppm. Moreover, if for example the count value of the referencecounter 82 is 9999990 (in decimal numbering) then the frequency of theoutput signal of the oscillation circuit 61 can be estimated to be fastby 1.0 ppm. The frequency of the output signal of the oscillationcircuit 61 accordingly needs to be corrected by this error amount,namely slowed by 1.0 ppm. Namely, the frequency correction amount is−1.0 ppm. The frequency error derivation processing is completed throughthe above processing.

When the frequency error derivation processing is completed, then atstep S107 (see FIG. 7), the control circuit 60 associates thetemperature measurement value acquired at step S103 with the frequencyerror derived at step 207, and stores these values in the roomtemperature register 73 when the temperature set for the constanttemperature chamber is room temperature, stores these values in the hightemperature register 74 when the temperature set in the constanttemperature chamber is a high temperature, and stores these values inthe low temperature register 72 when the temperature set in the constanttemperature chamber is a low temperature.

The semiconductor device 1 is sequentially placed in the constanttemperature chamber set with each of the temperatures, the lowtemperature, room temperature or the high temperature, set as thetemperature in the chamber, and the data storage processing programdescribed above is repeatedly executed. So doing results in the lowtemperature register 72, the room temperature register 73 and the hightemperature register 74 being stored with the temperature measurementvalues and the frequency errors of the oscillation circuit 61 in each ofthe temperature environment conditions.

Frequency Correction Processing

Explanation next follows regarding frequency correction processing inthe semiconductor device 1 after the above data storage processing hasbeen completed. The frequency correction processing is processingperformed to correct the frequency error arising in the output signalsof the oscillation circuit 61 and the frequency divider circuit 62caused by the frequency temperature characteristics of the oscillator28.

In a state installed in the integrating electricity meter 10 (see FIG.1), the control circuit 60 executes the frequency correction processingprogram every specific period of time, or during system reset and inresponse to input of a control signal through the leads 38. FIG. 10 is aflow chart illustrating a flow of processing of a frequency correctionprocessing program executed in the control circuit 60. This program ispre-stored on a storage unit of the control circuit 60.

At step S301, the control circuit 60 reads the temperature measurementvalues and the frequency errors stored in the low temperature register72, the room temperature register 73, and the high temperature register74.

At step S303, the control circuit 60 derives a relationship equation(frequency-temperature characteristics) between temperature andfrequency error in the oscillation circuit 61 based on the temperaturesand frequency errors read at step S301. FIG. 11 illustrates a graph ofthe relationship between temperature and frequency error (namelyfrequency-temperature characteristics) in an ordinary oscillationcircuit containing a tuning fork shaped quartz crystal oscillator. Thegraph illustrated in FIG. 11 is expressed by the following Equation (1).Note that in Equation (1), the f is the frequency deviation, a is aquadratic temperature coefficient, T is the measured temperature, T0 isa vertex temperature, and b is a vertex error.f=a×(T−T ₀)² +b  (1)wherein in Equation (1), a, T0 and b are constants determined accordingto the oscillator employed. These values fluctuate due to individualvariation between oscillators. It is accordingly possible to accuratelyderive the frequency-temperature characteristics of the oscillationcircuit 61 by deriving a, T0 and b based on measured values. The controlcircuit 60 derives the values of the a, T0 and b by substituting thefrequency errors and the temperature measurement values read from eachof the registers 72 to 74 as f and T in Equation (1), and therebyderives the relationship equation between temperature and frequencydeviation (the frequency-temperature characteristics) of the oscillationcircuit 61.

At step S305, the control circuit 60 acquires the temperaturemeasurement value by the temperature sensing device 27, and stores theacquired temperature measurement value in the temperature measurementvalue register 71.

At step S307, by substituting the temperature measurement value storedin the temperature measurement value register 71 into the relationshipequation derived at step S303, the control circuit 60 derives as thefrequency correction amount the frequency deviation at that temperature.The control circuit 60 then stores the frequency correction amount inthe frequency correction register 75.

At step S309, the control circuit 60 supplies the timer circuit 63 withcorrection data indicating the frequency correction amount stored in thefrequency correction register 75, thereby completing the currentroutine. The timer circuit 63 generates a timer signal of the frequencyof the output signal of the frequency divider circuit 62 corrected basedon the correction data supplied from the control circuit 60, andsupplies the timer signal to the later-stage power consumption meteringcircuit 22 (see FIG. 1).

Thus in the semiconductor device 1 of the present exemplary embodiment,the frequency errors in the oscillation circuit 61 in each of thetemperature environments, room temperature, low temperature, hightemperature are derived by actual measurements made on product shipment,and the frequency errors are stored together with the temperaturemeasurement values in the registry section 70. Then after productshipment, a frequency correction amount is derived from the relationshipequation between the temperature and the frequency error of theoscillation circuit 61 derived based on the data stored in the registrysection 70, and the frequency change component of the oscillationcircuit 61 due to temperature change is corrected according to thederived frequency correction amount, and a high precision timing signalgenerated.

As is clear from the above explanation, in the semiconductor device 1according to the first exemplary embodiment of the present invention,the temperature sensing device 27, the oscillator 28 and thesemiconductor chip 30 are sealed as a unit with the molding resin 32,and the semiconductor chip 30 is in-built with the oscillation circuit61, the frequency divider circuit 62 and the timer circuit 63.Accordingly, the time can be measured with only the semiconductor device1 mounted to the base board in the integrating electricity meter 10illustrated in FIG. 1. Namely, there is no need to separately mount theoscillator 28 and the frequency divider circuit 62 etc. to the baseboard. A saving is accordingly made in effort for connecting andadjusting between the oscillator and the frequency divider circuit.

Moreover, the temperature sensing device 27 is a discrete component as aseparate body to the semiconductor chip 30, and so in comparison to atemperature sensing device built into the semiconductor chip 30, theeffects of heat generated by the semiconductor chip 30 on thetemperature measurement values can be reduced. Moreover, making thetemperature sensing device 27 a separate body to the semiconductor chip30 enables a temperature sensing device with desired characteristics tobe selected. For example, it is possible to use a thermistor as thetemperature sensing device 27. Although there are thermistors that havea large change in resistance with temperature changes and smallvariation are available, an improvement in temperature detectionprecision can still be achieved in comparison to a temperature sensingdevice in-built into the semiconductor chip 30.

Moreover, since the temperature sensing device 27 and the oscillator 28are alongside each other on the first main face 25A of the die pad 26A,the temperature environments of the temperature sensing device 27 andthe oscillator 28 can be made to match each other. It thereby becomespossible to accurately measure the temperature of the oscillator 28using the temperature sensing device 27, enabling accurate correction tobe made of the frequency error the oscillation circuit 61 caused by thetemperature characteristics of the oscillator 28. Moreover, in thepresent exemplary embodiment described above, the resistor 271configuring the temperature sensing device 27 is configured directlyconnected to the die pad 26A. However, so as to achieve a similarconfiguration to that of the oscillator 28, configuration may be madewith a resistor 271 with external terminals sealed in a vacuum inside avacuum container (not illustrated in the drawings), and with the vacuumcontainer connected to the die pad 26A. The temperature environment ofthe resistor 271 can thereby be made to even more closely approach thetemperature environment of the quartz vibrating reed 281, and even moreaccurate frequency correction can be performed.

Moreover, the temperature sensing device 27 and the oscillator 28 aredisposed so as to partially overlap with the semiconductor chip 30mounted on the opposite side of the die pad 26A in a direction parallelto the first and second main faces, and so the package size can be madesmaller than in cases in which these member are all disposed side byside on the same face of the die pad 26A.

Moreover, the external electrodes 272 of the temperature sensing device27 and the external electrodes 285 of the oscillator 28 are exposedthrough the through holes 26C to 26F to the second main face 25B side ofthe die pad 26A mounted with the semiconductor chip 30. This therebyenables connection of the semiconductor chip 30 to the temperaturesensing device 27 and the oscillator 28 to be made using the bondingwires 53 a, 53 b without having to invert the lead frame 26 even thoughthe components are mounted on both faces of the lead frame 26. Moreover,according to such a configuration, the length of the bonding wires 53 a,53 b connecting the semiconductor chip 30 to the temperature sensingdevice 27 and the oscillator 28 can be made the minimum length. Thewiring resistance can thereby be reduced, enabling a configuration lessreadily affected by noise. Moreover, even though noise is readilygenerated between the bonding wires 52 that extend parallel to eachother, a 3-D intersection is achieved of the bonding wires 52 forconnecting together the temperature sensing device 27 and thesemiconductor chip 30 with respect to the bonding wires 53 a forconnecting together the oscillator 28 and the semiconductor chip 30 andthe bonding wires 53 b for connecting together the temperature sensingdevice 27 and the semiconductor chip 30. The accordingly enables theinfluence of noise to be reduced. Moreover, the temperature sensingdevice 27 and the oscillator 28 are closely adhered to the first mainface 25A of the die pad 26A, and so the capillary can be prevented fromcontacting edge portions of the through holes 26C to 26F during wirebonding.

Moreover, in the semiconductor device 1 according to the first exemplaryembodiment of the present invention, the control circuit 60 stores thefrequency errors of the oscillation circuit 61 from measurements atplural temperature environments, these being low temperature, roomtemperature and high temperature, in each of the registers 72 to 74, andderives the frequency-temperature characteristics of the oscillationcircuit 61 based on the stored frequency errors. Thus the controlcircuit 60 derives the frequency-temperature characteristics for eachdifferent oscillator by actual measurements, enabling accuratefrequency-temperature characteristics to be acquired. Moreover, thecontrol circuit 60 derives the frequency correction amount based on thederived frequency-temperature characteristics, and the timer circuit 63generates the timer signal in which the frequency of the output signalof the frequency divider circuit 62 has been corrected based on thisfrequency correction amount, thereby enabling more accurate timemeasurements to be performed.

Note that an explanation has been given in the above exemplaryembodiments of an example in which the relationship equation between thetemperature and the frequency deviation of the oscillation circuit 61 isderived in the frequency correction processing (see FIG. 10), howeverconfiguration may be made such that the relationship equation isdetermined during data storage processing performed prior to productshipment, and the derived relationship equation or the a, T0 and bstored in a register.

Second Exemplary Embodiment

Explanation follows regarding a semiconductor device according to asecond exemplary embodiment of the present invention. FIG. 12A is a planview illustrating a configuration of a semiconductor device 2 accordingto a second exemplary embodiment of the present invention, and FIG. 12Bis a cross-sectional diagram taken on line 12 b-12 b in FIG. 12A. Notethat in FIG. 12A and FIG. 12B, only the configuration on a die pad 26Ais selected for illustration, and leads 38, electrode pads 50, bondingwires 52 connecting together the leads 38 and the electrode pads 50, andmolding resin 32 as illustrated in FIG. 2 and FIG. 3 are omitted fromillustration. FIG. 13 is a block diagram illustrating a schematicconfiguration of the semiconductor device 2 according to the presentexemplary embodiment.

The semiconductor device 2 according to the present exemplary embodimentis configured including a semiconductor chip 30 and an oscillator 28mounted on a first main face 25A of the die pad 26A, and capacitors CGLand CDL mounted on the second main face 25B are included. Namely, thecapacitors CGL and CDL are in-built into the semiconductor chip 30 andthe oscillation circuit 61 of the first exemplary embodiment, however inthe present exemplary embodiment, the capacitors CGL and CDL areseparate from the semiconductor chip 30 and mounted on the second mainface 25B of the die pad 26A. The capacitors CGL and CDL configure anoscillation circuit together with the oscillator 28. Note that in thepresent exemplary embodiment a temperature sensing device (temperaturesensor) is in-built into the semiconductor chip 30.

There are through holes 26G, 26H, 26I formed in the die pad 26A throughfrom the first main face 25A to the second main face 25B. These throughholes 26G to 26I are respectively formed with rectangular shapes, andare arrayed along the Y direction. The semiconductor chip 30 and theoscillator 28 are disposed on the first main face 25A of the die pad 26Aalongside each other in the X direction in a state interposed betweenthe respective through holes 26G to 26I.

A region between the through holes 26G and 26H on the second main face25B of the die pad 26A configures a first capacitor mounting beam 43 athat serves as a first capacitor mounting region for mounting thecapacitor CGL. Similarly, a region between the through holes 26H and 26Iconfigures a second capacitor mounting beam 43 b that serves as a secondcapacitor mounting region for mounting the capacitor CDL. The capacitorCGL is joined on the second main face 25B side of the die pad 26A to thefirst capacitor mounting beam 43 a formed between the through holes 26Gand 26H. The capacitor CDL is joined on the second main face 25B side ofthe die pad 26A to the second capacitor mounting beam 43 b formedbetween the through holes 26H and 26I.

FIG. 14 is a perspective view illustrating a configuration of thecapacitors CGL and CDL. Note that in FIG. 14, the through holes 26G,26H, 26I formed to the die pad 26A and the capacitor mounting beams 43a, 43 b are illustrated together with the capacitors CGL and CDL. Thecapacitors CGL and CDL are surface mounted type ceramic chip capacitors,and are configured to respectively include ceramic dielectric bodies 291a, 291 b, and external terminals 292 a, 292 b provide at the two ends ofeach of the ceramic dielectric bodies.

The capacitor CGL is joined to the second main face 25B of the die pad26A so as to straddle the first capacitor mounting beam 43 a. The twoexternal terminals 292 a formed at the two ends of the ceramicdielectric body 291 a are accordingly respectively exposed to the firstmain face 25A side of the die pad 26A through the through holes 26G and26H. Similarly, the capacitor CDL is joined to the second main face 25Bof the die pad 26A so as to straddle the second capacitor mounting beam43 b. The two external terminals 292 b formed to the two ends of theceramic dielectric body 291 b are also accordingly exposed to the firstmain face 25A side of the die pad 26A through the through holes 26H and26I.

The oscillator 28 is mounted to the first main face 25A of the die pad26A such that external terminals 285 face upwards. One external terminal292 a of the capacitor CGL that is exposed to the first main face 25Aside through the through hole 26G is connected through a bonding wire 54to one of the external terminals 285 of the oscillator 28, and alsoconnected through a bonding wire 55 to an electrode pad 51C of thesemiconductor chip 30. Namely, the oscillator 28 and the semiconductorchip 30 are electrically connected together through one of the externalterminals 292 a of the capacitor CGL that is exposed to the first mainface 25A side through the through hole 26G. Similarly, one of theexternal terminals 292 b of the capacitor CDL that is exposed to thefirst main face 25A through the through hole 26I is connected to theother of the external terminals 285 of the oscillator 28 through thebonding wire 54, and connected to an electrode pad 51 c of thesemiconductor chip 30 through the bonding wire 55. Namely, theoscillator 28 and the semiconductor chip 30 are electrically connectedtogether through one of the external terminals 292 b of the capacitorCDL that is exposed to the first main face 25A through the through hole26I. The other external terminals 292 a, 292 b of the capacitors CGL andCDL that are exposed to the first main face 25A side through the centralthrough hole 26H are connected to an electrode pad 51 d of thesemiconductor chip 30 through a bonding wire 56. The electricalpotential of the electrode pad 51 d is fixed to ground level. The groundelectrical potential is accordingly applied to the other externalterminals 292 a, 292 b of the capacitors CGL and CDL. Note thatsimilarly to with the semiconductor device 1 according to the firstexemplary embodiment, the semiconductor device 2 according to thepresent exemplary embodiment executes data storage processing andfrequency correction processing, and high precision is secured in thefrequency of the timing signal output from the timer circuit 63 in thesemiconductor chip 30.

The capacitors CGL and CDL in the present exemplary embodiment arecomponents discrete from the semiconductor chip 30, thereby enabling thesurface area of the semiconductor chip 30 to be made smaller incomparison to when the capacitors CGL and CDL are in-built into thesemiconductor chip 30, and enabling the manufacturing cost to besuppressed. Moreover, making the capacitors CGL and CDL separate fromthe semiconductor chip 30 enables capacitors of desired characteristicsto be selected.

A tuning fork shaped quartz crystal oscillator, as illustrated in FIG.11, exhibits frequency-temperature characteristics such that theoscillation frequency in a low temperature region and a high temperatureregion is lower than that in a room temperature region. However, it isknown that in the oscillation frequency of an ordinary oscillationcircuit, the oscillation frequency becomes higher when the loadcapacitance is small. For example when a capacitor with temperaturecharacteristics such that the capacitance value in a low temperatureregion and a high temperature region is smaller than the capacitancevalue in a room temperature region, as illustrated in FIG. 15, isincorporated in an oscillation circuit, it is possible to employ thetemperature characteristics of the capacitors to cancel out the loweredportions of the oscillation frequency in the low temperature region andthe high temperature region caused by the temperature characteristics ofthe oscillator, enabling the frequency-temperature characteristics inthe oscillation circuit 61 to be made flat. For example, in a case inwhich a capacitor of about 10 pF is employed that has a capacitancevalue that is about 20% lower in the high temperature region and the lowtemperature region, then a cancelling out effect is expected in the hightemperature region and the low temperature region on the temperaturecharacteristics of about 10 ppm to 60 ppm. Flattening thefrequency-temperature characteristics of the oscillation circuit 61 isimportant in frequency error correction processing. Namely, in thesemiconductor device 2 according to the present exemplary embodiment,similarly to in the first exemplary embodiment, the temperature and thefrequency error of the oscillation circuit 61 is measured in each of thetemperature environments of room temperature, low temperature and hightemperature. When this is performed, if there are large frequencyfluctuations with respect to temperature changes then frequency errorsarising due to slight errors in temperature measurement cannot beignored. It is possible to raise the precision of frequency correctionby flattening the frequency-temperature characteristics of theoscillation circuit 61. For a capacitor with temperature characteristicsas illustrated in FIG. 15, barium titanate may for example be employedto give a laminated ceramic capacitor with X5S characteristics as adielectric body.

Moreover, the external terminals 292 a of the capacitor CGL and theexternal terminals 292 b of the capacitor CDL are exposed through thethrough holes 26G to 26I to the first main face 25A side of the die pad26A where the semiconductor chip 30 and the oscillator 28 are mounted.This accordingly enables the capacitors CGL and CDL to be connected tothe oscillator 28 and the semiconductor chip 30 by the bonding wires 54,55, 56 without having to invert the lead frame. Moreover, the oscillator28 and the semiconductor chip 30 are disposed so as to be interposedbetween through holes 26G to 26I, thereby enabling the length of each ofthe bonding wires 54, 55, 56 to be made a minimum length. The wiringresistance can be reduced thereby, enabling a configuration that is notreadily affected by noise. The capacitors CGL and CDL are closelyadhered to the second main face 25B side of the die pad 26A, and so thecapillary can be prevented from making contact with the edge portion ofthe through holes 26G to 26I during wire bonding.

Moreover, the oscillator 28 and the semiconductor chip 30 use theexternal terminals 292 a, 292 b of the capacitors CGL and CDL exposedthrough the through holes 26G and 26I as relay points during wirebonding. The vertex point of the bonding wires 53, 55 can accordingly beset lower than in cases in which the oscillator 28 and the semiconductorchip 30 are connected directly by bonding wires on the same face of thedie pad 26A. The thickness of the packaging of the semiconductor device2 can accordingly be made thinner.

Moreover, in the present exemplary embodiment, the external terminals292 a, 292 b of the capacitors CGL and CDL that are exposed to the firstmain face 25A side of the die pad 26A through the central through hole26H are connected through the bonding wires 56 to the electrode pad 51 dof the semiconductor chip 30 that is fixed to ground electricalpotential. As an alternative to such a configuration, as illustrated inFIG. 16, configuration may be made with the central through hole 26Heliminated, and one of the external terminals 292 a, 292 b of thecapacitors CGL and CDL may be connected to the die pad 26A with aconductive bonding material such as solder, so that the die pad 26A isfixed to the ground electrical potential. Adopting such a configurationenables the number of bonding wires to be reduced, and enables thepossibility of shorting between wires to be reduced.

Third Exemplary Embodiment

Explanation follows regarding a semiconductor device according to athird exemplary embodiment of the present invention. FIG. 17A is a planview illustrating a configuration of a semiconductor device 3 accordingto the third exemplary embodiment of the present invention, and FIG. 17Bis a cross-section taken along line 17 b-17 b of FIG. 17A. Note that inFIG. 17, only the configuration on the die pad 26A is selected forillustration, and leads 38, electrode pads 50, bonding wires 52connecting together the leads 38 and the electrode pads 50, and moldingresin 32 as illustrated in FIG. 2 and FIG. 3 are omitted fromillustration. FIG. 18 is a block diagram illustrating a schematicconfiguration of the semiconductor device 3.

The semiconductor device 3 according to the third exemplary embodimentdiffers from the semiconductor device 2 according to the secondexemplary embodiment in that, in addition to the capacitors CGL and CDL,a temperature sensing device 27 is mounted on a second main face 25Bside of the die pad 26A as a discrete separated body to thesemiconductor chip 30. Explanation follows regarding differences betweenthe semiconductor device 3 according to the present exemplary embodimentand the semiconductor device 2 according to the second exemplaryembodiment.

Through holes 26J and 26K are formed in the die pad 26A so as to passthrough from the first main face 25A to the second main face 25B. Thesethrough holes 26J and 26K are arrayed along the Y direction. The throughholes 26J and 26K are provided close together on a side facing towardsthe side of the semiconductor chip 30 on which the through holes 26G to26I are provided. Namely, the semiconductor chip 30 is provided betweenthe through holes 26G to 26I and the through holes 26J and 26K.

A region between the through holes 26J and 26K on the second main face25B of the die pad 26A configures a temperature sensing mounting beam 44serving as a temperature sensing device mounting region for mounting thetemperature sensing device 27. The temperature sensing device 27 is asurface mounted type of thermistor and is configured with a resistor andexternal terminals 272 provided at the two ends of the resistor. Thetemperature sensing device 27 is joined to the second main face 25B ofthe die pad 26A so as to straddle the temperature sensing mounting beam44. The two external terminals 272 formed to the two ends of thetemperature sensing device 27 are respectively exposed to the first mainface 25A side of the die pad 26A through the through holes 26J and 26K.

The external terminals 272 of the temperature sensing device 27 exposedto the first main face 25A side through the through holes 26J and 26Kare connected to temperature sensing device electrode pads 51 b of thesemiconductor chip 30 through bonding wires 57. Note that, similarly toin the semiconductor device 1 of the first exemplary embodimentdescribed above, data storage processing and frequency correctionprocessing is executed in the semiconductor device 3 according to thepresent exemplary embodiment, and high precision is secured in thefrequency of the timing signal output from a timer circuit in thesemiconductor chip 30

Thus in the semiconductor device 3 according to the present exemplaryembodiment, the semiconductor chip 30 and the oscillator 28 are disposedon the first main face 25A of the die pad 26A alongside each other inthe X direction, and the capacitors CGL, CDL are disposed on the secondmain face 25B of the die pad 26A alongside each other in the Xdirection, with the semiconductor chip 30 interposed between thecapacitors CGL and CDL and the temperature sensing device 27. Both thecapacitors CGL, CDL and the temperature sensing device 27 are configuredas discrete components separate to the semiconductor chip 30, such thatmore suitable components can be selected, and enabling the timemeasurement precision to be further raised. Moreover, according to thethird exemplary embodiment of the present exemplary embodiment, it ispossible to perform wire bonding without inverting the lead frame,similarly to in the first and second exemplary embodiments. Moreover, inthe present exemplary embodiment, placement of each of the component isdetermined such that the distance between the oscillator 28 and thetemperature sensing device 27 is comparatively long. In other words,placement of each of the component is determined such that the distancebetween the oscillator 28 and the temperature sensing device 27 islonger than the distance between the oscillator 28 and the semiconductorchip 30. This thereby enables the influence on the temperature sensingdevice 27 of noise arising from the oscillator 28 to the made smaller.Moreover, preferably the die pad 26A is fixed at the ground electricalpotential in order to prevent any noise arising from the oscillator 28being transmitted through the lead frame to the temperature sensingdevice 27. Moreover, placement may be made such that the semiconductorchip 30 is mounted on the first main face 25A of the die pad 26A and thecapacitors CGL, CDL and the temperature sensing device 27 are mounted onthe second main face 25B of the die pad 26A so as to partially overlapwith each other in a direction parallel to the first and second mainfaces. This thereby enables a more compact package size to be achieved.

Fourth Exemplary Embodiment

Explanation follows regarding a semiconductor device according to afourth exemplary embodiment of the present invention. In thesemiconductor device according to the first to the third exemplaryembodiments, the frequency correction processing is executed everyspecific cycle, and derivation is performed of a frequency correctionamount according to the peripheral temperature at each time of thefrequency correction processing. In contrast thereto, in thesemiconductor device according to the present exemplary embodiment,processing is simplified such that a new frequency correction amount isonly derived when a change amount from the temperature measured at theprevious time of frequency correction processing execution is a specificvalue or greater. When the change amount from the temperature measuredat the previous time of frequency correction processing execution isless than the specific value, the frequency correction amount derivedwhen the previous frequency correction processing was performed isemployed to perform frequency correction processing.

FIG. 19 is a functional block diagram of a semiconductor device 4according to the fourth exemplary embodiment of the present invention.The semiconductor device 4 differs from the semiconductor device 1 ofthe first exemplary embodiment described above in that a secondtemperature sensing register 77 is further included in a registrysection 70 (see FIG. 6). The second temperature sensing register 77 is aresistor that in frequency correction processing manages a temperaturemeasurement value acquired in the previous time of frequency correctionprocessing. Since other configuration elements other than the secondtemperature sensing register 77 are similar to those of thesemiconductor device 1 according to the first exemplary embodiment,explanation thereof is omitted. The semiconductor device 4 according tothe present exemplary embodiment does not derive a new frequencycorrection amount when the difference between the temperaturemeasurement value acquired during the current frequency correctionprocessing and the temperature measurement value acquired during theprevious time is lower that a frequency correction processing. Thefrequency correction amount derived during the previous time offrequency correction processing is accordingly applied as it is, andfrequency correction processing performed.

Explanation follows regarding frequency correction processing in thesemiconductor device 4 according to the present exemplary embodiment.Note that data storage processing (see FIG. 7) similar to that of thefirst exemplary embodiment is performed in preparation for thisfrequency correction processing, and a low temperature register 72, aroom temperature register 73 and a high temperature register 74 arestored with temperature measurement values and frequency errors of anoscillation circuit 61 acquired in each of the respective temperatureenvironments.

In a state inbuilt into an integrating electricity meter 10 (see FIG.1), a control circuit 60 executes a frequency correction processingprogram at each specific period, or at system reset or according to acontrol signal input through a lead 38. FIG. 20 is a flow chartillustrating a flow of processing of a frequency correction processingprogram according to the present exemplary embodiment executed in thecontrol circuit 60. The program is pre-stored on a storage means (ROM)of the control circuit 60. Moreover, a temperature measurement valueacquired in the previous time of frequency correction processing isstored in the second temperature sensing register 77.

At step S401, the control circuit 60 acquires the temperaturemeasurement value using the temperature sensing device 27, and storesthe acquired measurement value in the temperature measurement valueregister (the first temperature measurement value register) 71.

At step S402, the control circuit 60 reads the current time'stemperature measurement value stored in the temperature measurementvalue register 71 and the previous time's temperature measurement valuestored in the second temperature measurement value register.

At step S403, the control circuit 60 compares the previous time'stemperature measurement value read from the temperature measurementvalue register 71 against the current time's temperature measurementvalue read from the second temperature sensing register 77, anddetermines whether or not the difference therebetween is a specificvalue (for example ±1° C.) or greater. Namely, the control circuit 60determines whether or not the temperature change amount since theprevious time's frequency correction processing is a specific value orgreater. Processing proceeds to step S408 when the control circuit 60determines that the difference between the previous time's temperaturemeasurement value and the current time's temperature measurement valueis less than the specific value. However, processing proceeds to stepS404 when the control circuit 60 determines that the difference betweenthe previous time's temperature measurement value and the current time'stemperature measurement value is the specific value or greater.

At step S404, the control circuit 60 reads out the temperaturemeasurement value and the frequency errors stored respectively in thelow temperature register 72, the room temperature register 73 and thehigh temperature register 74.

At step S405, the control circuit 60 derives a relationship equation(frequency-temperature characteristics) representing the relationshipbetween the temperature and the frequency error in the oscillationcircuit 61 based on the temperature measurement values and the frequencyerrors read at step S404. Namely, the control circuit 60 derives thevalues of a, T0 and b by substituting the frequency errors read fromeach of the temperature registers 72 to 74 respectively as f and T inthe Equation (1). The relationship equation between the temperature andfrequency deviation (frequency-temperature characteristics) is therebyderived.

At step S406, the control circuit 60 derives, as the frequencycorrection amount, the frequency error at a temperature by substitutingthe current time's temperature measurement value stored in thetemperature measurement value register 71 into the relationship equationderived at step S405, and stores this frequency correction amount in thefrequency correction register 75.

At step S407, the control circuit 60 stores the current time'stemperature measurement value that is stored in the temperaturemeasurement value register 71 in the second temperature measurementvalue register. Namely, the value of the second temperature sensingregister 77 is replaced by the current time's temperature measurementvalue.

At step S408, the control circuit 60 reads the frequency correctionamount stored in the frequency correction register 75, supplies thisvalue to the timer circuit 63 and then ends the current routine. Thetimer circuit 63 generates a timing signal of the frequency of theoutput signal from the frequency divider circuit 62 corrected based onthe frequency correction amount supplied from the control circuitcontrol circuit 60, and supplies is corrected signal to the powerconsumption metering circuit 22 (see FIG. 1).

As is clear from the above explanation, in the semiconductor device 4according to the present exemplary embodiment, when the differencebetween the temperature measurement value acquired when executing thecurrent time's frequency correction processing, and the temperaturemeasurement value acquired when executing the frequency correctionprocessing the previous time is less than the specific value, thecontrol circuit 60 skips the processing of steps S404 to S407 (namelydoes not derive a new frequency correction amount), and supplies thefrequency correction amount already stored in the frequency correctionregister 75 to the timer circuit 63. Thus processing to derive thefrequency correction amount is omitted when a small temperature changehas occurred since when the frequency correction processing was carriedout the previous time, enabling a saving in power consumption to beachieve whilst still performing high precision time measurement. Thesemiconductor device 4 according to the present exemplary embodimentaccordingly does not perform derivation of the frequency correctionamount at a fixed interval. In order to execute processing irregularlyaccording to changes in the peripheral temperature, consideration mightfor example be given to a configuration provided with plural frequencydivider circuits, however the scale of the frequency divider circuitswould become large in such cases to try to always accommodate varioustemperature environments. The semiconductor device 4 according to thepresent exemplary embodiment enables optimum frequency correction to beperformed under various temperature environments without providingplural frequency divider circuits.

Note that although in the above exemplary embodiment derivation of a newfrequency correction amount was not performed when the difference of thetemperature measurement value to the temperature measurement valueacquired when executing frequency correction processing the previoustime is less than 1° C., it is possible to appropriately change thetemperature setting value used as the determination standard for whetheror not to perform frequency correction amount derivation. Moreover, thefrequency correction processing according to the present exemplaryembodiment may be implemented with any structure out of thesemiconductor devices 1 to 3 according to the first to the thirdexemplary embodiment.

Fifth Exemplary Embodiment

Explanation follows regarding a semiconductor device according to afifth exemplary embodiment of the present invention. It is known inoscillation circuits that employ quartz oscillators that deteriorationof the quartz oscillator over the years is a cause of changes inoscillation frequency. It is therefore preferable to periodicallycorrect the oscillation frequency of the oscillation circuit. There istherefore a need for an accurate clock to correct the oscillationfrequency of the oscillation circuit, and correcting oscillationfrequency with an accurate clock becomes difficult after shipping thesemiconductor device, or after installing the semiconductor device inthe installed device such as a measurement device. However in thesemiconductor device of the present exemplary embodiment, even withoutusing an accurate clock, it is possible to correct for not onlyfrequency changes caused by changes in temperature, but also to correctfor frequency changes caused by deterioration in an oscillator.

FIG. 21 is a functional block diagram of a semiconductor device 5according to a fifth exemplary embodiment of the present invention. Thesemiconductor device 5 differs from the semiconductor device 1 accordingto the first exemplary embodiment described above (see FIG. 6) in thatit further includes a timer counter 83 and a frequency shift amountregister 78 in the registry section 70.

The timer counter 83 is connected to a frequency divider circuit 62 andis a counter that performs time measurement based on an output signal ofthe frequency divider circuit 62. The timer counter 83 supplies thecontrol circuit 60 with cumulative time data that represents thecumulative time since for example the first time power was switched on,or since a reset input time.

The frequency shift amount register 78 is a dedicated non-volatilestorage medium (ROM) for reading out stored frequency shift amount datafor correcting for changes over the years in the oscillation frequencyof the oscillation circuit 61 that accompany deterioration of theoscillator 28 over the years. The frequency shift amount register 78 isconnected to the data bus 76, enabling the control circuit 60 to readfrequency shift amount data stored in the frequency shift amountregister 78.

Explanation follows regarding frequency shift amount data stored in thefrequency shift amount register 78. As described above, the oscillationfrequency of the oscillation circuit 61 shifts to the high frequencyside or the low frequency side accompanying deterioration over the yearsof the oscillator 28. One example of a cause of deterioration of theoscillator 28 over the years is adherence to the quartz vibrating reedof foreign bodies given off in minute amounts from for example thepackage. What is referred to as a shift in the oscillation frequency ofthe oscillation circuit 61 accompanying deterioration over the years inthe oscillator 28 means that the quadratic curve representing thefrequency-temperature characteristics illustrated in FIG. 11 is shiftedoverall in the up or down direction. The manner of change, such as theshift direction and shift amount of the oscillation frequency depends onsuch factors as the type of oscillator and the manufacturing method ofthe oscillator. However, there is not a large individual variationbetween the manner in which the oscillation frequency changes as long asthey are the same type of oscillator and use the same manufacturingmethod. The frequency shift amount register 78 is stored with estimatevalues of the frequency shift amount of the oscillation circuit 61 foreach specific period (for example every year) as frequency shift amountdata. The frequency shift amount of the oscillation circuit 61 forspecific periods may be known from executing accelerated aging testssuch as for example high temperature exposure tests. In the presentexemplary embodiment, the oscillation frequency of the oscillationcircuit 61 is confirmed by accelerated aging tests to shift by 0.6ppm±0.4 ppm each year, and 0.6 ppm is stored in the frequency shiftamount register 78 as the frequency shift amount data. When executingfrequency correction processing, the control circuit 60 reads thefrequency shift amount data stored in the frequency shift amountregister 78, and derives a frequency correction amount required tocorrect for the change over the years in the oscillation frequency ofthe oscillation circuit 61. The configuration elements other than thetimer counter 83 and the frequency shift amount register 78 are similarto those of the semiconductor device 1 according to the first exemplaryembodiment described above, and so further explanation thereof isomitted.

Explanation follows regarding frequency correction processing in thesemiconductor device 5 according to the present exemplary embodiment.Note that in advance of the frequency correction processing, datastorage processing is executed similarly to as in the first exemplaryembodiment described above (see FIG. 7), and temperature measurementvalues and frequency errors of the oscillation circuit 61 acquired undereach of the temperature environments are stored in a low temperatureregister 72, a room temperature register 73 and a high temperatureregister 74. Moreover, a frequency shift amount of 0.6 ppm every year isstored as the frequency shift amount data in the frequency shift amountregister 78.

In an installed state in an integrating electricity meter 10 (see FIG.1), the control circuit 60 executes a frequency correction processingprogram every specific period, or in response to input of a controlsignal through the lead 38, such as on system reset. FIG. 22 is a flowchart that illustrates a flow of processing of a frequency correctionprocessing program according to the present exemplary embodimentexecuted in the control circuit 60. The program is stored in advance ina storage means (ROM) of the control circuit 60.

At step S501, the control circuit 60 reads the temperature measurementvalues and frequency errors stored in each of the low temperatureregister 72, the room temperature register 73 and the high temperatureregister 74.

At step S502, the control circuit 60 derives a relationship equation(frequency-temperature characteristics) between temperature andfrequency deviation in the oscillation circuit 61 based on thetemperature measurement values and frequency errors read at step S501.Namely, the control circuit 60 derives values of the a, T0 and b bysubstituting the frequency errors and temperature measurement valuesread from each of the registers 72 to 74 as f and T in Equation (1), andthereby derives a relationship equation between the temperature and thefrequency deviation (frequency-temperature characteristics) in theoscillation circuit 61.

At step S503, the control circuit 60 acquires the temperaturemeasurement values by the temperature sensing device 27 and stores theacquired measurement values in the temperature measurement valueregister 71.

At step S504, the control circuit 60 substitutes the temperaturemeasurement value stored in the temperature measurement value register71 into the relationship equation derived at step S502, and derives apreliminary frequency correction amount (first frequency correctionamount) of the frequency deviation at that temperature, and temporarilystores this value in the frequency correction register 75.

At step S505, the control circuit 60 derives a frequency correctionamount (second frequency correction amount) corresponding to change overthe years by multiplying a notified cumulative time from the timercounter 83 by the frequency shift amount (0.6 ppm) stored in frequencyshift amount register 78. For example, in a case in which the notifiedcumulative time from the timer counter 83 is less than one year, thefrequency shift amount (0.6 ppm) stored in the frequency shift amountregister 78 is multiplied by 0 to derive 0 as the frequency correctionamount corresponding to the change over the years. However, when thecumulative time notified from the timer counter 83 is 1 year or more butless than 2 years, then the control circuit 60 multiplies the frequencyshift amount (0.6 ppm) stored in the frequency shift amount register 78by 1 to derive the frequency shift amount (0.6 ppm) corresponding to thechange over the years. Moreover, when the cumulative time notified fromthe timer counter 83 is 2 years or more but less than 3 years, then thecontrol circuit 60 multiplies the frequency shift amount (0.6 ppm)stored in the frequency shift amount register 78 by 2 to derive thefrequency shift amount (1.2 ppm) corresponding to the change over theyears.

At step S506, the control circuit 60 derives the final frequencycorrection amount by adding the frequency correction amountcorresponding to change over the years derived at step S505 (the secondfrequency correction amount) to the preliminary frequency correctionamount stored in the frequency correction register 75 (the firstfrequency correction amount), and stores the final frequency correctionamount in the frequency correction register 75.

At step S507, the control circuit 60 supplies the final frequencycorrection amount stored in the frequency correction register 75 to thetimer circuit 63 and ends the current routine. The timer circuit 63generates a timing signal of the frequency of the output signal of thefrequency divider circuit 62 corrected based on the frequency correctionamount supplied from the control circuit 60, and supplied the generatedcorrected timing signal to the power consumption metering circuit 22(see FIG. 1).

Thus, according to the semiconductor device 5 of the present exemplaryembodiment, since the oscillation frequency of the oscillation circuit61 is corrected for change over the years without employing an accurateclock, this enables time measurement to be performed at high precisionover a long period of time even after product shipment or afterinstalling in an apparatus.

Note that in the above exemplary embodiment, an example has beenillustrated in which the frequency correction amount corresponding tothe change over the years is derived by increasing the frequency shiftamount stored in the frequency shift amount register 78 for every year,in the series 1 times (0.6 ppm), 2 times (1.2 ppm), 3 times (1.8 ppm),and so on), however there is no limitation thereto. It is known that thechange over the years in the oscillation frequency of oscillationcircuits containing quartz oscillators are indications of the saturationcharacteristics. Thus the frequency shift amount for each year may bestored in advance in the frequency shift amount register 78 so as tomatch the saturation characteristics. For example, 0.6 ppm may be storedin the frequency shift amount register 78 as the frequency shift amountafter 1 year but less than 2 years, 0.4 ppm may be stored as thefrequency shift amount after 2 years but less than 3 years, 0.2 ppm maybe stored as the frequency shift amount after 3 years but less than 4years, and 0 ppm may be stored as the frequency shift amount after 4years. In such cases, the control circuit 60 derives 0.6 ppm as thefrequency correction amount corresponding to the change over the yearsafter 1 year but less than 2 year, derives 1.0 ppm (0.6+0.4 ppm) as thefrequency correction amount corresponding to the change over the yearsafter 2 years but less than 3 years, and derives 1.2 ppm (1.0+0.2 ppm)as the frequency correction amount corresponding to the change over theyears after 3 years. Moreover, the exemplary embodiment described aboveis an example in which the frequency correction amount corresponding tochange over the years is changed each time 1 year elapses, however thefrequency correction amount corresponding to the change over the yearsmay be changed at longer or shorter intervals than 1 year.

Moreover, although in the above exemplary embodiment, at step S506 thefinal frequency correction amount is computed by adding the frequencycorrection amount corresponding to the change over the years derived atstep S505 to the preliminary frequency correction amount stored in thefrequency correction register 75, there is no limitation thereto. FIG.23 is a flow chart illustrating another mode of frequency correctionprocessing according to the present exemplary embodiment.

At step S601, the control circuit 60 reads temperature measurementvalues and the frequency errors stored in the low temperature register72, the room temperature register 73 and the high temperature register74.

At step S602, the control circuit 60 derives a relationship equation(frequency-temperature characteristics) between temperature andfrequency deviation in the oscillation circuit 61 based on thetemperature measurement values and the frequency errors read at stepS601. Namely, the control circuit 60 derives values of the a, T0 and bby substituting the frequency errors and temperature measurement valuesread from each of the registers 72 to 74 as f and T in Equation (1), andthereby derives a relationship equation (frequency-temperaturecharacteristics) between the temperature and the frequency deviation.

At step S603, the control circuit 60 derives the frequency shift amountcorresponding to change over the years as a value obtained bymultiplying the notified cumulative time from timer counter 83 by thefrequency shift amount stored in frequency shift amount register 78. Forexample, in a case in which the notified cumulative time from the timercounter 83 is less than one year, the control circuit 60 derives afrequency shift amount of 0 corresponding to the change over the yearsby multiplying the frequency shift amount (0.6 ppm) stored in thefrequency shift amount register 78 by 0. However, when the cumulativetime notified from the timer counter 83 is 1 year or more but less than2 years, then the control circuit 60 multiplies the frequency shiftamount (0.6 ppm) stored in the frequency shift amount register 78 by 1to derive a frequency shift amount corresponding to the change over theyears (0.6 ppm). Moreover, when the cumulative time notified from thetimer counter 83 is 2 years or more but less than 3 years, then thecontrol circuit 60 multiplies the frequency shift amount (0.6 ppm)stored in the frequency shift amount register 78 by 2 to derive thefrequency shift amount corresponding to the change over the years (1.2ppm).

At step S604, the control circuit 60 corrects the relationship equationderived at step S602 using the frequency shift amount corresponding tochange over the years derived at step S603. Namely, at step S602, sincethe relationship equation between temperature and frequency deviationderived at step S602 does not include the change over the years, thecontrol circuit 60 makes an overall shift in the quadratic curve of thefrequency-temperature characteristics to reflect the component fromchange over the years by adding the frequency shift amount correspondingto the change over the years derived at step S603 to the apex error b ofthe relationship equation derived at step S602.

At step S605, the control circuit 60 acquires the temperaturemeasurement value of the temperature sensing device 27 and stores theacquired measurement value in the temperature measurement value register71.

At step S606, the control circuit 60 derives as a frequency correctionamount a frequency deviation at the relevant temperature by substitutingthe temperature measurement value stored in the temperature measurementvalue register 71 into the relationship equation corrected at step S604,and stores this in the frequency correction register 75.

At step S607, the control circuit 60 supplies correction datarepresenting the frequency correction amount stored in frequencycorrection register 75 to the timer circuit 63, and ends the currentroutine. The timer circuit 63 generates a timing signal that is thefrequency of the output signal of the frequency divider circuit 62corrected based on the correction data supplied from the control circuit60, and supplies these to the power consumption metering circuit 22 ofthe following stage (see FIG. 1).

Note that it is possible to implement the frequency correctionprocessing according to the present exemplary embodiment in a structureof any of the semiconductor devices 1 to 3 according to the first to thethird exemplary embodiments.

Sixth Exemplary Embodiment

FIG. 24 is a functional block diagram illustrating a configuration of asemiconductor device 6 according to a sixth exemplary embodiment of thepresent invention. The semiconductor device 6 differs from thesemiconductor device 1 according to the first exemplary embodiment inthe points that the semiconductor chip 30 includes an electrode pad 58connected to an output terminal of the oscillation circuit 61, and inthat it is not provided with a measurement counter or a referencecounter. The electrode pad 58 is connected to the lead 38 through abonding wire, thereby enabling external acquisition of the output signalof the oscillation circuit 61. In the present exemplary embodiment, thefrequency error of the oscillation circuit 61 is acquired for each ofthe temperature environments by measuring output signals of theoscillation circuit 61 externally acquired in each of the temperatureenvironments of low temperature, room temperature, and high temperature.Namely, the frequency errors of the oscillation circuit 61 in each ofthe temperature environments are acquired externally to thesemiconductor device 6. The frequency error of the oscillation circuit61 supplied from externally is stored as temperature measurement valuesin the low temperature register 72, the room temperature register 73 andthe high temperature register 74. According to the semiconductor device6 of the present exemplary embodiment, the derivation processing of thefrequency errors is performed externally, eliminating the need for themeasurement counter 81 and the reference counter 82 of the firstexemplary embodiment described above, and thereby enabling the size ofthe semiconductor chip 30 to be made smaller.

Modified Example

FIG. 25 is a perspective view illustrating a configuration of asemiconductor module 7 according to a modified example of the presentinvention. The semiconductor module 7 is configured including asemiconductor device 2 a mounted on a reference board 500, capacitorsCGL and CDL that are mounted on the reference board 500 and areconnected to the semiconductor device 2 a, and molding resin 510 thatserves as a sealing member for these members mounted on the referenceboard 500. The semiconductor device 2 a is the semiconductor device 2according to the second exemplary embodiment described above, with thecapacitors CGL and CDL removed. Namely, the semiconductor module 7 hasthe capacitors CGL and CDL of the semiconductor device 2 according tothe second exemplary embodiment described above removed and connected tothe semiconductor device 2 a on the reference board 500. According tosuch a configuration, although frequency correction processing cannot beexecuted by the semiconductor device 2 a on its own, it is possible toperform frequency correction as the semiconductor module 7.

Normally an exterior mounted metering apparatus such as an electricitymeter or a gas meter is liable to being affected by the externalenvironment. The resonance frequency of quartz oscillators widelyemployed for time measurement circuits fluctuates according theperipheral temperature. Thus the oscillation frequency of an oscillationcircuit including an oscillator changes according to peripheraltemperature variations. Thus accurate time measurements can no longer beperformed when the oscillation frequency of the oscillation circuitfluctuates. In particular, there is a need for measurement instrumentssuch as electricity meters to always perform time measurements at highprecision. To address this, semiconductor devices that include timingfunctions and are in-built into measuring instruments such aselectricity meters use temperature sensing devices (temperature sensors)to measure the temperature of the oscillator and to perform correctionfor the fluctuation amount in the oscillation frequency. In such cases,there is a need to accurately measure the temperature of the oscillatorusing the temperature sensing device in order to perform appropriatedfrequency correction.

For example, in a configuration with a temperature sensing devicein-built into an IC chip, it is difficult to accurately measure thetemperature of the oscillator due to the temperature sensing devicebeing affected by heat from the semiconductor chip. Moreover, as thetemperature sensing device in-built into a semiconductor chip there isthe assumption that utilization is made of one with temperaturecharacteristics of forward direction voltage VF in a pn junction,however it is difficult to perform temperature measurement at highprecision since the change in output signal with temperature of such atemperature sensing device is small and yet has a large variation. Thuswith a temperature sensing device in-built into a semiconductor chip, itis difficult to perform correction at high precision of the fluctuationamount of oscillation frequency accompanying changes in temperature.

However, in an oscillation circuit employing an oscillator such as aquartz oscillator, a capacitor for forming a resonance circuit isconnected to the oscillator. Building this capacitor into thesemiconductor chip enables the number of components to be reduced.However, the capacitor configuring the semiconductor needs to have acomparatively large surface area within the semiconductor chip, with anaccompany increase in the chip size. Consequently, sometimes building acapacitor into the semiconductor chip actually results in an increase incost. Moreover, a capacitor configuring a semiconductor has largervariation in capacitance values and larger capacitance value fluctuationto temperature changes compared to discrete components such a ceramiccondenser, making it difficult to make high precision changes in theoscillation frequency.

Thus although building a temperature sensing device and a capacitor intoa semiconductor chip enables a reduction to be made in the number ofcomponents, it becomes difficult to achieve high precision ofoscillation frequency of the oscillation circuit across the range ofusage temperatures, and it is difficult to perform accurate timingmeasurements.

The present invention provides a semiconductor device with a timemeasurement function capable of performing more accurate timingmeasurements, and a metering device including such semiconductor device.

What is claimed is:
 1. A semiconductor device comprising: an oscillator;a semiconductor chip that includes: an oscillation circuit that isconnected to the oscillator, a timer circuit that generates a timingsignal of a frequency according to an oscillation frequency of theoscillation circuit, and a frequency correction section that corrects afrequency of the timing signal based on temperature data; a lead framethat the oscillator and the semiconductor chip are mounted on, the leadframe having a through hole between the oscillator and the semiconductorchip, wherein the oscillator and the semiconductor chip are containedwithin a single package; and a bonding wire, the oscillator beingelectrically connected to the semiconductor chip through the bondingwire via the through hole, wherein the oscillator is mounted on a firstmain face of the lead frame, the semiconductor chip is mounted on asecond main face, that is on the opposite side of the lead frame to thefirst main face, the through hole is included between the oscillator andthe semiconductor chip in a direction that intersects with the firstmain face and the second main face, the through hole of the lead frameexposes a terminal portion of the oscillator to the second main faceside, and the bonding wire is connected to the terminal portion of theoscillator that is exposed to the second main face side through thethrough hole.
 2. The semiconductor device of claim 1, wherein thethrough hole includes two through holes, and the oscillator is mountedon a beam of the lead frame that is disposed between the two throughholes in a direction that is parallel to the first main face and thesecond main face of the lead frame.
 3. The semiconductor device of claim1, wherein the oscillator is provided at a position that overlaps withthe semiconductor chip in a direction parallel to the first main faceand the second main face.
 4. The semiconductor device of claim 1,further comprising: a temperature sensing device that detects aperipheral temperature, that supplies the detected temperature astemperature data to the frequency correction section, and that isprovided as a separate body from the semiconductor chip, the temperaturesensing device being mounted on the lead frame; and another bonding wireelectrically connecting the temperature sensing device to thesemiconductor chip.
 5. The semiconductor device of claim 4, wherein thetemperature sensing device is mounted on the first main face of the leadframe.
 6. The semiconductor device of claim 5, wherein the through holeincludes through holes with one of the through holes of the lead frameexposing a terminal portion of the temperature sensing device to thesecond main face side, and the another bonding wire is connected to theterminal portion of the temperature sensing device that is exposed tothe second main face side through the one through hole.
 7. Thesemiconductor device of claim 6, wherein the oscillator is mounted on abeam of the lead frame that is disposed between two of the through holesin a direction that is parallel to the first main face and the secondmain face of the lead frame, and the temperature sensing device ismounted on another beam of the lead frame that is disposed betweenanother two of the through holes in a direction that is parallel to thefirst main face and the second main face of the lead frame.
 8. Thesemiconductor device of claim 5, wherein the oscillator and thetemperature sensing device are provided at positions that overlap withthe semiconductor chip in a direction that is parallel to the first mainface and the second main face.
 9. The semiconductor device of claim 1,wherein the through hole is included between the oscillator and thesemiconductor chip in a direction that is parallel to the first mainface.
 10. The semiconductor device of claim 1, wherein the bonding wirepenetrates through the through hole to connect to the terminal portionof the oscillator.
 11. A metering apparatus, comprising: a semiconductordevice that includes: an oscillator; a semiconductor chip that includes:an oscillation circuit that is connected to the oscillator, a timercircuit that generates a timing signal of a frequency according to anoscillation frequency of the oscillation circuit, a frequency correctionsection that corrects a frequency of the timing signal based ontemperature data, and a measurement section that measures a measurementtarget associated with timing data generated based on the timing signal;a lead frame that the oscillator and the semiconductor chip are mountedon, the lead frame having a through hole between the oscillator and thesemiconductor chip, a bonding wire, the oscillator being electricallyconnected to the semiconductor chip through the bonding wire via thethrough hole, wherein the oscillator and the semiconductor chip arecontained within a single package, wherein the lead frame has oppositefirst and second main faces which are respectively on opposite first andsecond main face sides of the lead frame, the bonding wire is connectedto a terminal portion of the oscillator that is exposed to the secondmain face side, and the bonding wire penetrates through the through holeto connect to the terminal portion of the oscillator.
 12. Asemiconductor device comprising: an oscillator; a semiconductor chipthat includes: an oscillation circuit that is connected to theoscillator, a timer circuit that generates a timing signal of afrequency according to an oscillation frequency of the oscillationcircuit, and a frequency correction section that corrects a frequency ofthe timing signal based on temperature data; and a lead frame that theoscillator and the semiconductor chip are mounted on, the lead framehaving a through hole between the oscillator and the semiconductor chip,wherein the oscillator and the semiconductor chip are contained within asingle package, wherein: the oscillator is mounted on a first main faceof the lead frame, the semiconductor chip is mounted on a second mainface of the lead frame that is on a second main face side that is theopposite side of the lead frame to the first main face, the through holeis included between the oscillator and the semiconductor chip in adirection that intersects with the first main face and the second mainface, the through hole of the lead frame exposes a terminal portion ofthe oscillator to the second main face side, and the semiconductordevice further comprises a bonding wire connected to the terminalportion of the oscillator that is exposed to the second main face sidethrough the through hole.